Implantable medical devices (IMDs) such as cardiac pacemakers, implantable cardiovertor defibrillators (ICDs), implantable loop recorders (ILRs), implantable drug pumps, neurostimulators, etc. are generally provided by manufactures in a sterilized package. The package commonly includes an external carton or container for holding a sterilized inner tray or pouch containing the IMD. The IMD is sterilized within the inner tray or pouch using appropriate sterilization methods such as steam, gas or ultrasonic sterilization. The inner tray or pouch is generally provided with a peelable or tearable seal that can be opened to drop the sterile IMD contained therein into a sterile field without compromising the sterility of the IMD or the sterile field. For example, an IMD packaging tray having an open top may be sealed closed with a paper lid that is peeled back at the time of an implant procedure to allow the IMD to be dropped out of the tray into the sterile field.
Some packaging systems may include within the external carton or container an outer tray or pouch for carrying the sterilized inner tray or pouch. The inner tray or pouch and device contained therein may be sterilized within the outer tray or pouch. The outer tray or pouch may then be peeled open to drop the inner tray or pouch into the sterile field at the time of implant. An implanting physician or assistant may then open the inner tray or pouch within the sterile field.
Pre-implant testing, electrophysiological mapping, or system testing is commonly performed at the beginning of an implantation procedure to ensure that a patient meets implantation criteria and/or to determine an optimal implant location for the IMD and/or associated electrodes. Such testing may be performed using the IMD since using the IMD itself would generally provide the most reliable test results. However, during pre-implant testing, considerable care must be taken to ensure that the IMD and associated leads remain sterile for implantation. Once the IMD is removed from the sterile packaging, the IMD cannot be re-shelved should the patient not meet implantation criteria. As such, external equipment is often substituted for making physiological measurements or performing electrophysiological mapping. Use of external equipment for performing testing or mapping includes certain limitations, however, since the electronics of the external equipment will generally be different than the electronics of the IMD. Signals measured by external equipment may not be the same as signals measured at the same location by the IMD. Even minor signal differences can limit the usefulness or reliability of such measurements for the purposes of pre-implant tests.
Since IMDs tend to be costly devices, it is undesirable to open the IMD sterile packaging prior to knowing with reasonable certainty that the IMD is appropriate for the patient and that an acceptable implantation site for the device and/or leads can be identified. Furthermore, external equipment needed for performing pre-implant testing may not be readily available and requires extra space within the operating theater, which is often already crowded with equipment and personnel. Often a programmer that supports surface ECG recording in addition to receiving telemetry signals from the IMD is needed to perform pre-implant testing. Such full-function programmers can be bulky and costly to provide to all clinical centers.